HUNTSVILLE, Ala. (CBS/AP) Weeks before Alabama college professor Amy Bishop allegedly murdered three colleagues during a faculty meeting, she went to a shooting range to practice her aim, according to Bishop's husband.

His description of Bishop's "normal" demeanor leading up to Friday's shooting matched an account by a witness, who said the gathering was unremarkable until the gunfire broke out. Bishop, a Harvard-educated neurobiologist, is accused of shooting six people at the meeting, three fatally. Two of the survivors remained in critical condition Monday.

Bishop's husband, James Anderson, said he knew his wife had a gun, but didn't know when or how she got it. "I really don't know how she got it, or where she got it from," he told The Associated Press on Monday in an interview at his home.

Police have previously said Bishop had no permit for the gun they believe she used in the shooting, and investigators said they didn't know where she got it.

Bishop's husband said nothing unusual happened on their trip to the shooting range, and that she didn't reveal why she took an interest in target practice.

Nothing in her behavior in the days before the shooting foreshadowed the violence last week, either, he said. "She was just a normal professor," he said.

Investigators haven't commented on a possible motive, but Bishop was vocal among colleagues about her displeasure over being denied tenure by the university, forcing her to look for work elsewhere after this semester.

Bishop had several disturbing events in her past. In 1986, she shot her brother to death. It was ruled an accident. In 1993, police questioned her after a colleague received a pipe bomb. The bomb didn't go off. No one was charged.

Bishop is currently charged with one count of capital murder, which can lead to a death sentence in Alabama if convicted, and three counts of attempted murder. The list of charges are likely to grow.

Killed were Gopi K. Podila, the chairman of the Department of Biological Sciences, and professors Adriel Johnson and Maria Davis. Two of the wounded — professor Joseph Leahy and staffer Stephanie Monticciolo — were in critical condition Monday. The third, Luis Cruz-Vera, had been released from the hospital.